Blue - green algae are callled cyanobacteria because they

Options

A. Are not green
B. Do not have nucleus
C. Do not produce gametes
D. Are as small as bacteria.(M.P.P.M.T.2012)

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Cyanobacteria":**
- Cyanobacteria are commonly referred to as blue-green algae. The term "cyanobacteria" reflects their color and classification.

2. **Color and Pigments:**
- Cyanobacteria contain two main types of pigments:
- **Phycocyanin** (which gives them a blue color)
- **Chlorophyll** (which gives them a green color).
- The presence of these pigments is why they are referred to as blue-green algae.

3. **Prokaryotic Nature:**
- Cyanobacteria are prokaryotic organisms, meaning they lack a true nucleus and other membrane-bound organelles. This characteristic is a defining feature of the Monera kingdom.

4. **Unicellular Organisms:**
- They are primarily unicellular, although some can form colonies. This unicellularity is similar to bacteria, which is why they are grouped with them.

5. **Reproduction and Gametes:**
- Unlike many eukaryotic algae, cyanobacteria do not produce gametes. Instead, they reproduce asexually, which is another characteristic that aligns them with bacteria.

6. **Nitrogen Fixation:**
- Some cyanobacteria can fix atmospheric nitrogen, which is an important ecological function, but this does not directly relate to their naming.

7. **Conclusion:**
- Therefore, blue-green algae are called cyanobacteria primarily because they do not have a true nucleus and share characteristics with bacteria.

**Final Answer:**
Blue-green algae are called cyanobacteria because they lack a true nucleus and are prokaryotic in nature.

---